Audi balanced mobility

Audi wants to take the lead in the automotive industry regarding sustainable approaches to the use of natural resources. Under the motto of “Audi balanced mobility,” the company is gearing its efforts to pursue a major goal: completely CO₂-neutral mobility.

The Audi e-gas project, the initial phase of which is now underway, is a cornerstone of the master plan. Audi is the world’s first premium automotive manufacturer to set up a portfolio of sustainable sources of energy – starting with wind power. This portfolio will be rounded out by clean power, hydrogen and methane. These three sources will make mobile the electric, fuel-cell and methane vehicles of the near future. This new technology offers additional, significant potential: it can aid the energy-supply industry in solving the problem of how to store clean power.

Wind turbines constitute the first component of the Audi e-gas project. Audi is investing in four large power plants at an offshore wind park in the North Sea. Each new wind turbine generates 3.6 megawatts and can collectively produce some 50 GWh of electricity annually – enough to meet the demand of a medium-sized city. Just a portion of this green power would be enough to manufacture 1,000 units of the A1 e-tron and propel them 10,000 km (6,200 miles) a year – as per the maxim that electric vehicles from Audi ought to run primarily on sustainably generated electricity.

The project’s second component is Audi’s e-gas plant. The first plant of its kind in the world is scheduled to go into operation in Werlte, Germany in 2013. Ground will be broken in July 2011; Audi is investing several tens of millions of euros in the plant’s construction. Construction of additional plants is expected in the medium term. Four project partners are on board with Audi: Stuttgart’s SolarFuel GmbH; the Centre for Solar Energy and Hydrogen Research (ZSW), also based in Stuttgart; the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in Kassel, Germany; and EWE Energie AG.

The e-gas plant will comprise two main components, the first of which is an electrolyzer. It will run on clean power – some of which will be electricity generated by Audi’s nearby wind turbines. Aided by polymer electrolyte membranes, the electrolyzer splits water into its components: hydrogen and oxygen. In the future, hydrogen can power fuel-cell vehicles such as the Audi Q5 HFC. Hydrogen is not, however, used directly during the project’s first phase; it is instead placed into a storage tank and then the methanation unit.

The methanation unit thermochemically combines the hydrogen with carbon dioxide to create methane – synthetic natural gas. The e-gas plant is connected to a waste-biogas plant, which supplies the required CO₂ that would otherwise be emitted into the atmosphere and pollute it. Rated at 6.3 MW, the plant in Werlte is expected to produce some 1,000 metric tons of methane annually while consuming 2,800 metric tons of CO₂. In January 2011, Audi set up a lab facility in Werlte with an output of 25 kW for testing purposes. It was possible straightaway to manufacture methane of the required quality.

The methane created from renewable sources and known at Audi as e-gas is fed into Germany’s natural-gas network and therefore the network of CNG stations as well, where methane replaces fossil-based natural gas imported from abroad. In the future, this new fuel will power Audi’s specially modified natural-gas vehicles such as the A3 TCNG, scheduled to hit the market in 2013.

The projected quantity of e-gas produced at the plant could propel 1,500 units of the A3 TCNG 15,000 km (9,320 miles) annually – with 150 metric tons of e-gas left over.

This surplus can be stored in the public gas network and then be used as needed by other consumers such as block-type thermal power stations, which can utilize the surplus gas to produce green power and heat on overcast days with little wind.

The Audi e-gas project has the potential to solve the most pressing problem confronting Germany’s sustainable energy-supply industry. Although the future belongs to renewable sources of energy, production is subject to natural fluctuations. Existing means of storage, such as pumped-storage power plants, can handle only a tiny fraction of renewable power, and the expansion of capacities will result in increasingly larger surpluses.

Methanation using renewable energy solves this problem: the power grid is coupled with the underground gas network, which can store surplus power supplies for months. The gas network bears tremendous potential: 220 terawatt hours (TWh) in contrast to electricity-storage systems, with a capacity at present of just 0.04 TWh. Energy can be discharged from the gas network, converted back to electricity, and returned to the power grid at any time, as needed.

The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors excepted.